Hard watch case

ABSTRACT

A watch case resistant to mechanical defacement and corrosion, having an external pressed and sintered component at least a part of which comprises at least one material selected from the group consisting of A12O3, BeO, CeO2, Cu2O, Cr2O3, CoO, Fe2O3, Fe3O4, MgO, MnO, NiO, Nb2O3, SiO2, Ta2O5, ThO2, SnO2, TiO2, V2O3, ZnO, ZrO2, A12O3. SiO2, A12O3. TiO2, BeO.A12O3, CoO.A12O3, MgO.A1203, MgO.ZrO2.SiO2, ZnO.A12O3 and ZrO2.SiO2.

United States Patent Kasai et al.

[451 Sept. 12, 1972 [54] HARD WATCH CASE [72] Inventors: Masami Kasai, Yoshiaki Fujimori,

born of Nagano, Japan [73] Assignee: Kabashiki Kaisha Suwa, Seikosha Tokyo, Japan Filed: Jan. 29, 1971 Appl. No.: 110,960

[30] Foreign Application Priority Data Jan. 30, 1970 Japan ..45/7674 [521 US. Cl. .58/88 R, 58/88 G Int. Cl. ..G04b 37/00 Field of Search ..58/88, 90 R, 106.5; 117/129,

References Cited UNITED STATES PATENTS 7/1958 Long ..117/12'9 3/1954 Grubeletal ..117/129x 3,179,524 4/1965 Hunter ..l17/129X 3,482,951 12/1969 I-Iubbelletal. ..l17/129X FOREIGN PATENTS OR APPLICATIONS 3,079 3/1891 Switzerland ..58/88 Primary Examiner-Richard B. Wilkinson Assistant Examiner-George H. Miller, Jr. Attorney-Blum, Moscovitz, Friedman & Kaplan 57 ABSTRACT BeO'A1- B(3, COO-A1 0 MgO'A1 0 MgO'ZrO -SiO ZnO-AI BDS and zro,-sio,.

1 1 Claims, 4 Drawing Figures lll 1 HARD WATCH CASE BACKGROUND OF THE INVENTION In the mass production of conventional watch cases the materials which have been used principally are gold, gold alloy and stainless steel. All of these materials, however, have a low surface hardness (Vickers hardness, 200 maximum); as a result, they are easily scratched or otherwise defaced by contact with other hard metals or concrete. The high surface polish is lost relatively quickly during the wearing of the time-piece. Moreover, using the above-mentioned metals the case color is restricted either to those of gold or stainless steel. Furthermore, gold and its alloys have high specific gravities as is shown in Table I. In consequence, large watch cases can be sufficiently heavy to constitute an annoyance to the wearer. Also, gold and its alloys are expensive.

SUMMARY OF THE INVENTION We have found that a number of oxides which have hitherto been used for the manufacture of brick, board, crucibles, and refractory tools can be fashioned into parts of watch cases or entire watch cases which are mechanically strong, resistant to abrasion, and resistant to corrosion. Suitable oxides maybe the oxides of single metals such as Al or compounds as in the case of LII Mg0'Al 0bt3. Also oxides may be used along or in combination. These oxides, when pressed and sintered, are very hard, resistant to corrosion and mechanical defacement and make available a choice of colors.

TABLE I Characteristics of Various Materials For a Watch Case Specific Hardness Materials Gravity (Knoop) Color (gl WC 15.8 1880 Black Al,O, 3.9 1930 Pure White ZrO, 5.4 (7) Yellow MgO-AhO, 3 .3 (8) Colorless 18-8 Stainless Transparent Steel 7.9 200 Gray Au 19.3 50 Yellow Note: FIGURES in shown Mohs hardness.

Table I also gives data for tungsten carbide and for stainless steel and for gold. As is evident from the table tungsten carbide and gold are much heavier than the representative oxides tabulated. While the carbide is hard as shown by the corresponding entry in the table, stainless steel and gold are soft.

It is ,an object of the invention to provide a watch case of improved hardness, durability, chemical stability and appearance.

It is a further object of the invention to provide a watch case of low weight.

It is another object of the invention is to provide a A hard, durable, abrasion-resistant surface element of attraetive appearance for watch cases of conventional materials.

Still other objects and advantages of the invention will in part be obvious and will in part be apparent from the specification.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a sectional view of a watch case in which a composition in accordance with the present invention is used as a surface protection;

FIG. 2 is a sectional view of a watch case in which a bezel of a composition in accordance with the present invention is used to protect the top surface of a case of conventional composition;

FIG. 3 is a sectional view of a watch case in which an element having a composition in accordance with the present invention is used to protect the upper and side surfaces of a watch case of conventional composition; and

FIG. 4 is a sectional view of a watch case, the entire body of which is made of a composition in accordance with the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS A mixture of powdered raw material having a particle size of l-2 microns and consisting of 94 percent by weight of A1 0 3 percent by weight of SiO 1 percent by weight of MgO, 0.5 percent by weight of TiO;, and 1.5 percent by weight of Fe O is pulverized and mixed in a ball mill for about 100 hours. A lubricant, preferably of the paraffin group, is added to make the mixture suitable for pressing. The material is formed into the desired shape at a pressure of about 2 tonlcm The composition is then sintered for about an hour at a temperature of 1650" to 1750 C. The resultant product is extremely hard and is then diamondpolished. The product is sapphire blue in color and has a Vickers hardness of 1650 to 1730. As a result of this great hardness, the surface resists scratching by knife, razor, scissors, glass or file. In addition to being resistant to mechanical defacement, the material also shows excellent resistance to artificial sweat and sea water. The material can therefore be considered sufficiently resistant to corrosion to be suitable for use as a watch case. The specific gravity of the product is about 4.0 g/cc so that product cases are substantially lighter than conventional cases of stainless steel, gold, or gold alloy. Such cases are also lighter than cases made of carbide when sintered with heavy metal binders such as nickel, cobalt or molybdenum.

In another embodiment, powdered raw material having a particle size of 1-2 microns and consisting of percent by weight of MgO'Al O 3.5 percent by weight of SiO 0.5 percent of C00 and 1.0 percent of MnO is treated in a manner similar to that described above. The product of this example is also very hard and, can be polished only with diamond. The product has a Vickers hardness of 1780 to 1860, its color is a beautiful blue, and its specific gravity is 3.8g/cc. It should be noted that this example differs from the previous example in that a compound oxide, namely MgO'Al O is used as the principal ingredient.

Materials which may be used alone or in combination are the simple oxides, A1 0 BeO, CeO Cu O, ch03, COO, F6203, F6304, MIIO, Nbzog, Slog, Ta2O Thoz, S1102, TIOZ, V203, ZI'IO and ZI'OZ,

and the compound oxides Al O -SiO2, AlzO -Tioz, BeO-Al O COOAIZO3, Mgo-ZrOy be used in combination with simple oxides. Also, the,

metals to the combination of the oxides and compound.

oxides examples of such metals are Ni, Co, and Mo.

In particular, the hardness may be very substantiallyincreased by adding boron to compositions.

In view of the great hardness and low deformabilifi/ of compostions prepared in accordance with the present invention it is desirable that the design of the watch case take these properties into account. In FIG. 1, the hard layer 1 is superimposed on a case body 2 of stainless steel. The hard layer 1 is attached to the case body 2 by cementing. The case body, being of stainless steel, is easily fabricated and the upper surface of the 'case is protected from marring by the superimposed hard layer 1.

In FIG. 2 the protective layer 1 is in the form of a bezel covering most of the outer surface of the case body 2. The bezel is held to the body 2 by means of the snap-ring 3. Since the bezel is essentially non-deformable, deformability must by provided in the body; deformability of the body is provided bymeans of the groove 4 behind the snap-ring 3.

In the example of FIG. 3 the outer case body 1 and the lug 5 are composed of materials of the type described herein. The body 2 is made of stainless steel which, as mentioned above, is easily processed.

Grooves 3 and 4 are cut into the peripheral portion of 1 the inner case body and serve to permit insertion of a' binding agent for holding the outer case to the inner case body.

FIG. 4 shows a watch case in which the entire body including the back cover is made of one of the hard materials described herein. In a watch case of this design, no part of the case can be scratched.

It will thus be seen that the objects set forth above,

among those made apparent from the preceding description, are efficiently attained and, since certaini changes may be made in the above composition of j external component is cemented to said stainless steel the above description shall be interpreted as illustrative and not in a limiting sense.

What is claimed is: 1. A watch case resistant to mechanical defacemertt and corrosion, having an external pressed and sintered component at least a part of which comprises at least one material selected from the group consisting of ihlgog, CeOz, CUZO, ch0 COO, PC2013, F6 0 MgO, MnO, NiO, Nb o SiO Ta O T1102, S1102, Tiog, V203, Z110, ZI'OZ, A1203 Slog, A1 0 TiO BeO A1 0 C00 A1 05, MgO -Al O MLO ZIOg SiO2, ZIIO A1203 and ZI'Og Slog.

2. A watch case as defined in claim 1 wherein said external component chiefly comprises the simple oxides listed in claim 1.

3. A watch case as defined in claim 1 wherein said external component chiefly comprises the compound I oxides listed in claim 1.

4. A watch case as defined in claim 1 further comprising a metal selected from the group consisting of 5 Ni, Co and Mo.

5. A watch case as defined in claim 1 further comti l 285231 case as defined in claim 1 wherein said external component includes a case cover and a case body.

7. A watch case as defined in claim 6 wherein said case cover and case body are of one-piece construction.

8. A watch case as defined in claim 1 further comprising a stainless steel body, the outer portion of which is covered by said pressed and sintered external component.

9. A watch case as defined in claim 8 wherein said pressed and sintered external component is a bezel.

10. A watch case as defined in claim 8 wherein said external component is mechanically engaged with said stainless steel body.

11. A watch case as defined in claim 8 wherein said body.

UNITED STATES PATENT OFFICE CERTIFICATE 0F ,CORECTION Patent No. 3 ,690, 062 Dated Sept 12 1972 Inventor) Masami Kasai, Yoshiaki Fuj imori It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

In the Abstract, line 8, "A1 13 (3" should read "A1 0 line 9, "Al BD3" should read "A1 0 Signed and sealed this 12th day of February 1974.

(SEAL) Attestz' EDWARD M.FLET( IHER,JR. c. MARSHALL DANN Attestlng Offlcer Commissioner of Patents FORM P0-1050 (10-69) uscoMM-oc 60376-P69 LLS. GOVERNMENT PRINTING OFFICE: I969 O-866-334,

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3 ,690, 062 Dated Sept 12 1972 I v t r( Masami Kasai, Yoshiaki Fuj imori It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

In the Abstract, line 8, "A1 15 (3" should read "A1 0 line 9, "Al BDB" should read "A1 0 Signed and sealed this 12th day of February 1974.

(SEAL) Attest:

EDWARD.M.FLET(PHER,JR. C. MARSHALL DANN Attestlng offlcer Commissioner of Patents FORM PC4050 (10-69) USCOMWDC 6376 P69 1* us. GOVERNMENT PRINTING or-ncz: I969 o-sss-az-u, 

2. A watch case as defined in claim 1 wherein said external component chiefly comprises the simple oxides listed in claim
 1. 3. A watch case as defined in claim 1 wherein said external component chiefly comprises the compound oxides listed in claim
 4. A watch case as defined in claim 1 further comprising a metal selected from the group consisting of Ni, Co and Mo.
 5. A watch case as defined in claim 1 further comprising boron.
 6. A watch case as defined in claim 1 wherein said external component includes a case cover and a case body.
 7. A watch case as defined in claim 6 wherein saiD case cover and case body are of one-piece construction.
 8. A watch case as defined in claim 1 further comprising a stainless steel body, the outer portion of which is covered by said pressed and sintered external component.
 9. A watch case as defined in claim 8 wherein said pressed and sintered external component is a bezel.
 10. A watch case as defined in claim 8 wherein said external component is mechanically engaged with said stainless steel body.
 11. A watch case as defined in claim 8 wherein said external component is cemented to said stainless steel body. 